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Friday, August 19, 2011

It's my crab in a box!

That's right, it's the Box Crab! Specifically, we'll be learning about the

Brown Box Crab

Lopholithodes foraminatus

During my first semester working in the wet lab at UAS (Juneau), two fishermen came in and handed me a bag with what they originally thought had been a rock. Turns out it was a female brown box crab, doing what she does best:

sadly I didn't take a picture of her, but this is what she looked like ^^

Pretty tight, right? Box crabs, as you may have noticed, can package themselves up, protecting their legs from curious passersby. But how do they respirate while they're all squared away? Brown box crabs have two circular openings that form when they tuck themselves in called foramen through which water can circulate.

you can see the curvature on the legs and

the purplish hue where the foramin will form

tah-dah! one box crab, complete with the ability to get water to its gills!

Brown box crabs range from Kodiak, AK to Sand Diego, CA. They are clammers (like Billy Joel, for all you Long Islanders out there. True story, I totally saw Billy clamming outside his house once in Oyster Bay. But back to the crabs.) using their chelae to dig through the sediment and crush their prey. They also eat brittle stars and urchins, and they are preyed upon mainly by octopus. Another animal using (and abusing) the brown box crab is the blacktail snailfish, who apparently likes to lay its eggs IN the brown box crab gills!?! I'm not sure how this happens (read more here), but I guess that, while the eggs may collapse some of their gill filaments, the crabs are able to survive the intrusion.

a golden king crab with its gills exposed to show snailfish eggs. ouch!

Now these box crabs aren't to be confused with the Calappa sp. box crabs; brown box crabs are lithodids, related to king crabs! You can kind of see the resemblence in their rostrums (noses), which might also explain why the brown box crab's other common name is the Oregon queen crab.